Proud of his ability to withhold sea-sickness, David Whitley took on his greatest challenge – the ferry across the Foveaux Strait

The forewarning had been ample. Before stepping on the catamaran, I knew that if one boat trip was going to force me to reconsider my opinion of my constitution, this would be it.

While not claiming an iron stomach, I have generally been sick about once every three years during my adult life – and this includes some fearsome binge drinking as a student and backpacker. Sea sickness, though? I’ve a pretty darned strong record. I vaguely remember a small maritime upchuck as a child, but beyond that I’ve been a model of seaborne fortitude.

The Foveaux Strait between New Zealand’s South Island and Stewart Island, a 39km stretch of often vicious, wind-swept sea, has a long track record of destroying such reputations. Smack bang in the middle of the Roaring Forties – a latitude that gives albatrosses much delight and sailors the tremors – the Strait is something only reluctantly tackled by the Stewart Islanders themselves.

It only took a few minutes for things to get somewhat lurchy. The skipper had set course across some might big swells, the catamaran bounding upwards and downwards like a carriage on a big dipper. Huge dousings of spray splashed violently all the way up the glass windows, everyone inside rather thankful that they didn’t have to be out on deck. And any thoughts of going to the bar for a pint were quickly disregarded.

Spotting the regulars was a fairly simple task. One old guy slurped merrily at his coffee looking entirely unperturbed. The skipper stared out to the horizon with sturdy determination. The couple in front seemed to enter a well-honed meditation technique.

Elsewhere, however, the inexperience was shining through like a beacon. One woman and her daughter sat out at the back, clearly hoping that fresh air would make things less grotesque, yet failing to follow the standard advice of looking out directly at the horizon. The Japanese couple in the middle didn’t seem to have any strategy at all. They simply looked terrified.

There was a crushing inevitability hanging in the air. Once someone’s stomach gave way, everyone’s would.

After about 20 minutes, the first victim fell. The Japanese woman reached for the sick bag, and sent the wafting smell of vomit across the boat. She spent the next 40 minutes making her way through an impressive collection of bags, most dutifully handed to her by her husband until he too succumbed.

Behind, the bravery of a couple taking four children on the ferry quickly started to look like foolhardiness. The crying started, the stomachs churned and the junior travellers started adding to the victim count. At one delightful moment, one poor boy missed the sick bag and coated his mother’s hand.

As the journey began to draw to an end, I was left thankful that the one hour catamaran trip had replaced the two-to-three hour ferry ordeal of days gone by. My stomach was giving notice. I wasn’t going to last too much longer. Around 50% of the passengers had gone, and I was pretty sure I’d be next.

Then came merciful relief. The battering calmed as the catamaran eased into port at Bluff. I was a survivor. Brimming with pride, as I stepped off, I asked one of the crew how bad that journey was, comparatively.

After conflicting reports, David Whitley takes on the Tongariro Crossing (well, half of it) on New Zealand’s North Island.

“The Tongariro Crossing is for pussies”, I had been told elsewhere in New Zealand. “If you want to spend your day in a queue of people walking across a mountain, then great. But it’s really not that much of a challenge.”

The Tongariro Crossing is the big boy, sat high on the pedestal waiting to be shot at. It has long been one of New Zealand’s prescribed must-dos, and this status means it attracts both flak and tens of thousands of people wanting to take it on every year.

When half of it is closed due to volcanic activity – as is currently the case – there must be a temptation to file it in the overrated basket and skip it.

It’s when you get to the south crater that you realise succumbing to that temptation would have been a terrible mistake. Yes, you’ve hardly got it to yourself and, yes, the severity of the uphill grind to get there is vastly overstated. But my word, the scene is magnificent.

The South Crater is a vast flat, dust-blown field. A white track, created by footfall crosses the centre of it, and tufts of hardy grass manage to poke through an otherwise totally barren landscape. It looks like the sort of giant amphitheatre that would be used for some ultra-bloodthirsty Colosseum-style entertainment by an evil galactic emperor in a sci-fi film.

To the left, Mount Tongariro slowly climbs towards its summit. To the right, Ngauruhoe soars upwards, the perfect volcanic cone. It’s merely a vent of Tongariro, but it is higher. Small figures can be seen on its slopes, attempting to crawl up the brutal scree at a 45 degree angle. It’s a dangerous undertaking – rocks regularly tumble down into the would-be climbers’ path.

The figures are humans, but I half expect them to be Hobbits. Ngauruhoe doubled as Mount Doom in the Lord of the Rings films. Peter Jackson and co had to do surprisingly little to make it look so deadly and forbidding.

The rest of Mordor comes into view as we climb along the ridge that leads out of South Crater. Over to the west is the Oturere Valley, a black and bumpy place formed by centuries of spilling lava.

Mordor is not the goal, though – the Red Crater summit is. And the views from there are so remarkable that I want to yabber about them to everyone I’ve ever met, whilst simultaneously weeping and drooling. Behind, the iron oxide stains the Red Crater a deep crimson. A sweep round brings into view Ngaurohoe, and Tongariro’s summit. But it’s the no-go zone ahead that’s the cherry on top. Inside the stark central crater, the Emerald Lakes dazzle with seemingly impossible intensity – the blue and green colours alarmingly vivid.

Beyond, looking deceptively close, but an hour’s walk away, is the Blue Lake. And behind it is the reason we can go no further. A white cloud rises above the water. It’s the Te Maari crater, which erupted twice in 2012 and is now being carefully monitored as it continues to let off steam.

It’s a reminder of where this landscape of lava flows, rusty orange rivers and bleak, rocky plains came from. And it’s a reminder that it has not finished changing.

We have to turn back. It’s not yet safe to make the full crossing. But despite occasionally having to wait for other people to go past or get out of the way of your photo, and despite not being the grand physical endurance test some people build it up to be, there are few places on earth that can compare. It’s not a walk into the unknown and it’s not a walk into solitude, but it’s a walk into something truly special.